Question 214347
Let x=number of students in school
(2/5)x=number of girls
(1/2)(2/5)x==(1/5)x=number of girls who took part
Then (3/5)x=number of boys
And (1/2)(3/5)x=(3/10)x=number of boys who took part
So our equation to solve is:
(1/5)x+(3/10)x+570=x  multiply each term by 10
2x+3x+5700=10x subtract 10x and also 5700 from each side
2x+3x-10x+5700-5700=10x-10x-5700 collect like terms
-5x=-5700  divide each side by -5
x=1140------------------------------------number of students in school

CK
(1/5)*1140+(3/10)*1140+570=1140
228+342+570=1140
1140-1140


Hope this helps---ptaylor